Patent GB-964875-A (GB)
Title: Improvements in or relating to electrophotography
Inventor: CASSIERS PAUL MARIA
IPC: G03G5/07
Filed: 1959-02-26
Abstract: N-(b -Hydroxypropyl)-carbazole is made by reacting carbazole with propylene oxide in the presence of sodium amide and ferric nitrate. Dehydration with phosphorus pentoxide yields N-propenyl-carbazole.ALSO:A polymeric photoconductive composition contains a polymeric material as below, with or without a sensitiser (see below), a plasticizer (phthalates and phosphates specified), a pigment and/or an agent controlling viscosity, free flow, ageing, thermal stability, oxidation or gloss; the polymer is one having as recurring units <FORM:0964875/C3/1> where A is a direct linkage or a divalent radical such as CH2, CO, OCO, CH2CH2COO, CH2CH (CH3)OCO, CH2C6H4 or CH2CH2COC6H4, R is H or methyl, R1 is H, methyl or ethyl, Z is S or a direct linkage, Z1 is N or CH (not CH if Z is S), and Q1, Q2, Q3 and Q4 represent the connections to aromatic rings. Another polymeric photoconductor may be present, especially a polymer of a vinyl-substituted aromatic ketone as in Specification 964,877. The preferred photoconductors are polymers, copolymers and graft copolymers of N-vinyl-carbazole, but others are mentioned in which the ringsystem is carbazole, phenthiazine or fluorene. Polyvinylcarbazole itself is covered by Specification 856,770, and the present invention therefore deals with this only when present as a copolymer or as a mixture with another polymer of the formula quoted above. It is stated that the polymers may be made by normal methods in solution or emulsion, initiated by free radicals, ion-formation or radiation. Among the many polymers listed the preparation of the following is given in detail: poly-N-allyl-carbazole, poly-N-propenyl-carbazole, copolymer of N-vinyl-carbazole and ethyl acrylate, copolymer of N-vinyl-carbazole and methyl methacrylate, copolymer of N-vinyl-carbazole and isobutyl methacrylate, and a graft copolymer of N-vinyl-carbazole and polyvinyl butyral. Many suitable sensitisers are mentioned, these being dyestuffs of the di- and tri-aryl-methane, rhodamine, mono- and poly-methine, azine, azo, anthraquinone, indigo and phthalocyanine series, stilbenes (e.g. as in Specification 964,874), mono- and polycyclic aromatic compounds, negatively substituted aliphatic compounds such as iodoform, tetracyano-ethylene and succinic acid, azomethines, pyrazines, pteridines, triazines, furans, tetrazolium salts, diazonium salts, carbazoles, oxadiazoles (e.g. as in Specification 851,218), oxazoles, thiazoles, imidazoles (e.g. as in Specification 964,873), pyrazoles, inorganic compounds such as ammonium persulphate, potassium bromate and Sky Blue pigment (cobalt stannate), and the compounds mentioned as sensitisers in Specification 964,873. Instead of using the polymers as such, suitable monomers or mixtures of monomers and polymers can be applied to a support and polymerized, condensed or cross-linked in situ. Suitable solvents for casting the polymers on to a support are benzene, toluene, acetone, methylene chloride, chloroform, dioxan, tetrahydrofuran, dimethylformamide and glycol monomethyl ether. Polymers used in the examples (apart from those mentioned above) are copolymers of N-vinyl-carbazole with methyl, butyl or 2-ethylhexyl acrylate and a terpolymer of N-vinyl-carbazole, styrene and acrylonitrile. An additional polymer that may be present is a terpolymer of vinyl chloride, vinyl acetate and maleic anhydride. The Provisional Specification describes the preparation and use of polyvinylcarbazole itself.  Specifications 681,432, 686,733, 883,787 and 883,788 also are referred to.